This research is aimed at elucidating the molecular mechanisms that control axonal growth and regeneration in the CNS. The main experimental systems to be used are nerve growth cones (GCPs) isolated from fetal rat brain and cultures of fetal rat cerebral cortex. Phospholipid transmethylation (an enzyme activity activated by nerve growth factor in PNS growth cones) in GCPs is to be used in a biochemical assay to screen for and isolate a CNS-active neuronotrophic factor. Various purative signal transduction mechanisms will be investigated biochemically in GCPs. Parallel experiments will be designed to study the effects on growth cone chemotaxis and membrane expansion of agents that block or stimulate specific steps of transduction mechanisms. Such steps include: phospholipid transmethylation, Ca2+ flux, protein kinase activities, phospholipase A2. The methodologies will involve subcellular fractionation, nerve tissue culture, techniques for protein and lipid analysis, video-enhanced light microscopy, and electron microscopy. The combined biochemical and microscopic studies should eventually lead to the isolation of growth factor(s) active on CNS neurons and the identification of the transducer mechanisms regulating vectorial growth of these neurons. Ultimately, this research is expected to lead to the design of causal therapies to promote regeneration after CNS injury and to reverse degenerative disorders of the CNS.